Health Team

CDC investigating mutated flu virus in NC

Posted March 28, 2011 3:55 p.m. EDT
Updated March 28, 2011 11:03 p.m. EDT

— State and federal public health officials are examining a cluster of influenza B viruses found only in North Carolina that appear to be less responsive to a common antiviral drug than typical flu viruses.

A genetic change in the viruses not seen in samples from other states makes them harder to treat with Tamiflu, officials said Monday.

"These particular viruses are less sensitive to the drug in the lab, but they are not resistant,” Dr. Zack Moore of the state Division of Public Health said in a statement. “We want to assure physicians and their patients that antiviral drugs remain an effective treatment for influenza.”

Thirty-one viruses with this genetic change were collected from 92 samples from North Carolina patients between November and February.

"The reason we do this is to try to detect small changes early on and see if they have any clinical significance or not," said Dr. Megan Davies, chief epidemiologist for the Division of Public Health.

Most of the patients had typical flu symptoms and recovered after several days, but one patient who had severe underlying immune problems died shortly after being diagnosed with influenza, officials said.

The U.S. Centers for Disease Control and Prevention is testing more influenza B viruses from North Carolina and surrounding states to determine whether the same genetic change can be found elsewhere.

State and federal officials have advised physicians to follow existing antiviral guidelines, but to consider this new information when caring for North Carolina patients who are hospitalized with severe influenza B infections.

Moore emphasized that while influenza B infections have been common during this flu season, it does not present a greater risk to individuals than other flu strains. Flu cases are on the decline across the state, officials said.